A conveying system of the above type is described in detail in particular in the following patent publications:
DE 36 06 129 A1; EP 1 187 781 B1; DE 36 12 765 A1; U.S. Pat. Nos. 6,831,566; 5,460,261; 7,259,854; EP 0 336 385 B1; WO 2008/034483 A1; U.S. Pat. Nos. 6,291,991; and, 7,178,663 B2.
The carrying-side and running-side covering plates of a conveyor belt, as core component of a conveying system, normally consist of a rubber mixture containing a rubber component or a rubber component blend, a crosslinking agent or crosslinking system, comprising a crosslinking agent and an accelerator, and normally further mixture ingredients, in particular a filler and/or a processing aid and/or an aging prevention agent and/or plasticizer and/or other additives (for example, fibers, colored pigments). The rubber base in this connection is in particular:
natural rubber (NR)butadiene rubber (BR)chloroprene rubber (CR)styrene-butadiene rubber (SBR)nitrile rubber (NBR)butyl rubber (IIR)ethylene-propylene rubber (EPM)ethylene-propylene-diene rubber (EPDM)SBR/NR blendSBR/BR blendNR/BR blend
Of particular importance hitherto was CR, which is distinguished by a high resistance to flame, weathering and aging, in particular for conveyor belts with use in underground mining. At the present time, the SBR/NR material base is increasingly becoming exceptionally important.
As a result of the vulcanization of a rubber mixture of the aforementioned type, the conveyor belt is given the necessary elastic properties.
The conveyor belt is normally further provided with an embedded tension carrier or reinforcement. The tension carriers used in the conveyor belt longitudinal direction are cords of steel or aramid running in parallel, cords made of steel being of particular importance. The tension carrier can, however, also be a single-layer or multilayer textile structure, in particular in the form of a fabric. Of particular importance here is a polyamide-polyester fabric. In particular in conjunction with steel cord conveyor belts, for the purpose of split prevention, in addition use is made of a transverse reinforcement made of synthetic cords, for example of polyamide (PA), embedded in the carrying-side and/or operating-side covering panel (WO 2008/034483 A1).
In addition, the following components can also be embedded in the carrying-side and/or running-side covering plate: conductor loops, transponders, barcodes, a polymer matrix with detectable particles or other detectable elements mixed in. In this regard, reference is made in particular to the following patent publications: DE 44 44 264 C1; DE 197 15 703 A1; U.S. Pat. Nos. 7,954,632; and, 6,781,515.
The conveyor belt can further be provided with a built-on part, for example with an entrainer, guide part and with edge and side wall profiles. Built-on parts of this kind comprise a polymer material (elastomer, thermoplastic elastomer, thermoplastic) and, on the foot-end thereof, are adhesively bonded to the carrying-side surface of the elastic conveyor belt. Built-on parts of this kind are described in particular in the following patent publications: DE 32 19 170 A1; DE 34 14 285 A1; DE 10 2009 025 906 A1; and, DE 10 2009 025 911 A1.
Further components of a conveying system can be:                reversing rollers or reversing drums        hold-down rollers in the case of tubular conveyor belt systems        correction rollers, in particular in tubular conveyor belt systems        chutes        monitoring devices        
With regard to the monitoring devices, the following possibilities with comprehensive development activities are to be mentioned in particular:                In the case of monitoring the damage to the carrying-side and/or running-side covering plates, use is made of optoelectronic systems, in particular in the form of a line or area-scan camera, reference being made in particular to the following patent publications in this regard: DE 24 13 543 A1; DE 101 29 091 A1; DE 42 40 094 A1; DE 101 40 920 A1; U.S. Pat. No. 6,702,103; EP 1 187 781 B1; U.S. Pat. Nos. 6,831,566; 7,259,854; United States patent application publication 2003/0000808; and, WO 2008/031648 A1        Of increasing importance is the inspection of a conveyor belt by means of high-energy radiation, in particular x-rays. A device of this type is described in particular in the following patent publications: DE 35 17 314 A1; U.S. Pat. No. 8,149,989; JP 04158208 A (Patent Abstracts of Japan); and, JP 2000292371 A (Patent Abstracts of Japan).        
In the following text, a particular system problem will now be discussed in more detail.
In particular, in underground hard-coal mining, safety has the highest priority. Because of the easy combustibility of the coal, flame prevention is one of the greatest requirements. For the transport of coal, use is made of conveyor belts which can run over many kilometers. Were a conveyor belt to catch fire, it would propagate the flames over great distances.
In order to prevent this, conveyor belts in most countries are subject to strict fire-related requirements. In addition, sprinkler installations and other precautions for preventing and extinguishing flames are used.
The greatest danger of flame initialization originates from the formation of sparks by friction between a conveyor belt and a driving drum, reversing drum, carrying rollers and deflecting rollers or deflecting drums. It is possible for the conveyor belt to be blocked by external action; however, the driving drum, driven by a motor, continues to run. Or else, a reversing or deflecting drum is blocked while the conveyor belt continues to run. As a result of the high contact pressure of the conveyor belt, specifically on the drums, which results in a high development of heat, sparks easily occur, which can trigger a fire. The danger of spark formation is provided in particular when easily ignitable materials such as coal dust are located on the belt or the drum. Complete removal of coal dust is not possible in coal mining underground.